I will have to disagree with you on this. I have a UPO 45 bought it back in 2007, the only mods done are dial relume, gen crown, tube and the pearl, has been service twice taken up to 100 feet dive.
I will tell you this puppy is 100% waterproof. I am not sure why would you want to change the HE valve I can't even tell the difference myself. all of the reps are pretty good at keeping water unless poor assembly otherwise it should be waterproof.
my two cents